New generation RIBA hepatitis C strip immunoblot assays

Area of Science:

• Virology
• Immunology
• Diagnostic Assays

Background:

• Second-generation hepatitis C virus (HCV) Elisas are now used in Europe and under review in the US.
• These assays incorporate additional antigens (nucleocapsid and NS-3 regions) alongside the first-generation c100-3 antigen.

Purpose of the Study:

• To evaluate the performance of second-generation HCV Elisas and supplementary tests in screening blood donors.
• To characterize changes in the repeat reactive donor population using new diagnostic markers.

Main Methods:

• Screening of random volunteer blood donors using the Ortho second-generation HCV Elisa (2-Ortho HCV Elisa).
• Confirmation and characterization of reactive samples using the second-generation RIBA HCV strip immunoblot assay (2-RIBA HCV SIA) with four recombinant antigens (5-1-1, c100-3, c33c, c22-3).

Main Results:

• The 2-Ortho HCV Elisa detected a substantial change in the repeat reactive donor population.
• A large number of samples reactive in the 2-RIBA HCV SIA for second-generation antigens (c33c, c22-3) were identified by the 2-Ortho HCV Elisa.
• The percentage of indeterminate samples (reactive to only one HCV antigen) was higher with the second-generation assay (approx. 25%) compared to first-generation Elisas (approx. 5%).
• Indeterminate samples in the second-generation assay were predominantly reactive to c22-3, unlike first-generation assays where c100-3 was dominant.

Conclusions:

• Second-generation HCV Elisas offer improved detection capabilities but result in a higher rate of indeterminate results.
• The shift in antigen reactivity in indeterminate samples highlights the evolving landscape of HCV diagnostics.
• Further investigation is warranted to understand the clinical significance of these indeterminate results.